Blue billy goat weed
Vascular – Exotic
Herbs - Dicotyledonous composites
Terrestrial. Prefers open sunny spots along forest edges.
Erect or ascending annual herb, up to 1 m tall somewhat woody toward base. leaves on a short petiole up to 20 mm long. Leaves hairy and glandular especially on lower surface, ovate with crenate-serrate margins up to about 50 x 60 m. Blue flowers in dense clusters. Seeds sparsely hairy, black up to 1.8 mm long.
Is distinctive within the Asteracea due to the blue flowers, and petiolate, hairy leaves with toothed margins.
January, February, March, April, May, June, July, August, September, October, November, December
Annual. Produces small dry seed, sparsely hairy at one end. Dispersed by people and the wind.
Mexico, C. and tropical America
Reason for introduction
ageratum: From the Greek a- ‘without’ and geras ‘old’, meaning not aging, possibly referring to the fact that the flowers do not wither readily
houstonianum: Named after the genus Houstonia, which is named after the English botanist Dr William Houston.
References and further reading
Johnson, A. T. and Smith, H. A (1986). Plant Names Simplified: Their pronunciation, derivation and meaning. Landsman Bookshop Ltd: Buckenhill, UK.